1. Field of the Invention
The present invention relates to a drive arrangement for a motor vehicle connectable to a crankshaft of an internal combustion engine and having a clutch system which includes an electric machine for damping torsional vibrations.
2. Description of the Related Art
A prior art clutch system with a flywheel mass is disclosed, for example, by German reference DE 196 09 043 C1. This flywheel mass device includes a first flywheel mass and a second flywheel mass. A primary flange which is permanently connected to a crankshaft of an internal combustion engine is part of the first flywheel mass which can be rotated relative to the second flywheel mass. These two flywheel masses form the flywheel disk of a friction clutch which is connected downstream from the flywheel masses. The second flywheel mass, also referred to as the secondary flywheel mass, can be connected to an output drive shaft via the friction clutch. The disadvantage with this type of prior art clutch system is that the damping capacity of the flywheel mass device is frequency-dependent. In particular, the damping capacity is limited at a maximum to predeterminable frequency ranges.
A prior art drive arrangement for hybrid vehicles is disclosed in German reference DE 43 23 601 A1 and comprises an internal combustion engine which can be coupled to an output drive shaft via an interposed clutch. This drive arrangement also includes an electric machine comprising a rotor designed as an external rotor which is connected to the output drive shaft. A friction clutch is arranged radially inside of the electric machine. When the clutch is disengaged, the electric machine does not influence the rotational behavior of the crankshaft. Rotational nonuniformities in the crankshaft may cause a tumbling movement of the crankshaft. The tumbling movement may severely load the bearings of the crankshaft and of the internal combustion engine and may cause nonuniform wear of the friction clutch, particularly the friction linings, during a clutch reengagement operation.
Because of the recent developments relating to ever more economical drive systems in relation to fuel consumption, internal combustion engines are becoming less and less uniform in terms of their rotational behavior. Such rotational nonuniformities may lead to severe loading of components in the drive train as mentioned above may result in premature material fatigue.